It is known at present that a water-cooled internal combustion engine cylinder head has a cooling water cavity, for example, the specifications and their accompanying drawings of Chinese Patent ZL200720139399.7 and ZL200410082513.8 disclose a horizontal single-cylinder water-cooled diesel engine. The sectional view of the water-cooled cylinder head in the drawings of the above-said patents shows that the cooling water cavity of the cylinder head surrounds the outside walls of fuel injector receiving holes, the outside walls of intake ducts, and the outside walls of exhaust ducts, and has a complicated configuration and shape. Thus, the water-cooled cylinder head can only be formed by means of a core of the cooling water cavity. The core needs using sands and binders, and the casting process and the dust generated during breaking and removing the core may pollute the environment. Moreover, because of the complicated design configuration of the water-cooled cylinder head of the prior art, it is rather difficult to make demoulding and to take out the cores, and so it is impossible to employ die-casting process to form the cylinder head. A cylinder head, formed by die-casting process, for an air-cooled single-cylinder diesel engine is disclosed in the specification and its accompanying drawings of Chinese Patent ZL94194819.6, in which a complicated helical-shaped intake duct is formed, for the first time, by die-casting process with taking out a core section by section. Further, the specification and its accompanying drawings of patent application No. 200480042175.3 disclose a method of die-casting the whole cylinder head of an air-cooled diesel engine and the die-casting mould used in the method. At present, both the water-cooled/air-cooled internal combustion engine cylinder blocks and the air-cooled internal combustion engine cylinder heads have been manufactured in great batches by die-casting process with aluminum alloys. Now, it is necessary to create a new water-cooled cylinder head configuration and a new technical solution for making it, so as to facilitate mass production of the water-cooled cylinder heads by die-casting process while meeting the requirements to ensure the functions which the water-cooled internal combustion engine cylinder head should have. Furthermore, the new technical solution should be reliable, simple and practical in production, better economical, energy-saving, environmentally-friendly, and easy to realize mass production.